Revision as of 01:45, 12 August 2012

Page in development so far just layout

The intention of this page is to provide the detail of making a working SD card for a RaspberryPi keeping instructions and explanations jargon free as much as posible and explaining any neccessary jargon as it appears.

Getting an image

What is an image.

An image is a file you download that contains the bare minimum to setup a RaspberryPi SD card. The SD card is that bit of plastic you can put in your camera to store pictures and it is more than capable of acting as the primary disk for your RaspberryPi

The absolute minimum to load a Wheezy image is a 2 Gig (Gigabyte) SD card (there are images that will fit on a 1 Gig but not Wheezy) but you will not have much space so I reccomend a 4 Gig and as a noob have two if you can.

You can move to bigger ones later I started with a 2 Gig I extracted from an old camera and a 4 Gig I scrounged from an old MP3 player

If you have a camera that takes SD cards use the cameras format option its quick and usually works.

Ok most of this page will work around the Wheezy images but should work for any image but your going to need to get an image.

The Wheezy image at this time has two versions and each has two download methods

Both give the option of a direct browser download or a download using Torrent.

Torrent is better for the community if you know how to use it but if you do not just let your browser do the work and take the Direct Download either way you will end up with a zip file.

Do not unzip yet you need to do a check on this zip file before you unpack (unzip) it.

The checksum and using it

On the download page you will see a long string with the name SHA-1 this is the checksum if you think any computer file is a sequence of numbers if you were to add all of those together you would get a result an answer.

Get one of the numbers wrong and the answer is wrong well the SHA-1 is a hexadecimal (base16) total for the zip file you downloaded.

This is actually a lie SHA1 is actually a fancy algorithim called a Secure Hash Algorithm but of which there are four. As a noob don't worry it is all done for you.

There is a little program SHA1SUM.exe that if you feed it your zip file will calculate an SHA-1 number and if that number is the same one on the download page you can be confident the download worked correctly.

Highlight and copy the checksum create a new text file (I use wordpad) and paste the checksum into it, it may add some leading space so delete that highlight and copy it with the leading spaces removed save the file and when asked for the file name paste in the checksum followed by .txt

you now have a text file that has the checksum as the name and it contains the checksum this is slightly safer than writing it down. Also if you feel inclined it is easy to print a hard copy.

So you should now have copy of sha1sum.exe and a copy of its checksum

Double click sha1sum.exe you should get a pop-up window (you may get the unknown publisher one first and if you are running vista or Windows7 you will need to run as administrator)

The resuting window has two boxes and two buttons [select file] and [exist] (an unusual spelling of exit) click select file and browse to yor sh1sum.exe file and click. There should now be the file name in the top window and a value in the bottom window and because you used the checksum as a file name it will be fairly easy to compare the two if they are the same then you know sha1sum.exe is good.

So you now need to do the same for your downloaded image zip file. (NOTE the zip file not the extracted image file). it may be worth doing the little text file trick for your Wheezy image sha1 check value.

This is where this may sound patronising but remember each file has its own sha1 value.

If the values come out the same you can be confident the download was a sucess and it will be safe to unzip the downloaded file.

Unzipped you will end up with a file that ends .img this is the file you are going to build into your SD card but first you need a program to do this.

Image writers

Image writers are programs used to stuff a .img file onto an SD card or a pen drive.

There are two options in Linux

dd which is command line and not the easiest for the noob feel free to investigate but the following is the command line description for running dd

dd bs=1M if=[debian .img file] of=[path to your SD card]

and

There is a gui tool under the Ubuntu banner called ImageWriter (To use this you will need to add this into Ubuntu and it can be found in the Ubuntu Software Centre under Accessories) This is intuitive compared to dd.

One easy one for Windows

This is Win32DiskImage there are a number of locations you can get this